The invention relates to an operating mechanism of a multipole electrical circuit breaker, comprising:
a pair of parallel support plates between which the mechanism is housed,
a toggle formed by a pair of first and second rods articulated together by means of a first pivoting spindle,
a switching bar mechanically coupled to the first rod, and acting as support for the movable contacts of all the poles, said bar being mounted in rotation around a second parallel spindle, to ensure closing and opening of the contacts,
a tripping hook pivotally mounted between a charged position and a tripped position around a third spindle of the support plates, and articulated simultaneously on the second rod,
an operating handle securedly united to a base articulated on a fourth fixed spindle of the support plates,
a latch cooperating with an end of the tripping hook to form a mechanical latching in the charged position,
a connecting spring anchored between the first spindle and the base of the handle,
and a locking lever cooperating with the bar to block the base in an intermediate position S of the handle when the contacts are welded, said locking lever being pivotally mounted on a fifth spindle of the support plates, and comprising a stop able to occupy a first active position or a second inactive position according to the angular position of the bar.
The U.S. Pat. No. 3,605,052 describes a circuit breaker of the kind mentioned in which the position of the operating handle gives a reliable visual indication of the position of the components constituting the circuit breaker. The operator can thus detect a malfunctioning, notably welding of the contacts, and any resetting or movement of the handle to the open position is then rendered impossible by the presence of the locking lever which blocks the handle in the intermediate position. The locking lever is pivotally mounted on a spindle of the support plates, and is controlled by a feeler according to the angular position of the bar. This feeler is formed by a simple tab resting on the upper face of the bar. The handle returns automatically to the closed position by the action of the connecting spring of the mechanism.
The U.S. Pat. No. 2,262,859 provides in addition an initial pretripping commanded at the beginning of the movement travel of the handle, followed by blocking of the handle by the locking device.
The U.S. Pat. No. 5,142,112 describes a fork-shaped locking lever cooperating with the switching bar. The whole surface of the fork surrounds the bar when the latter is in the closed position of the contacts. In case of normal opening of the contacts, the bar drives the locking lever to the unblocking position right at the beginning of the opening travel. This results in anticipated unblocking of the locking lever, before formation of the disconnection distance required between the separated contacts.